Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Saeed bin Musayyib that the Holy Prophet (peace and blessings be upon him) instructed Hazrat Attab bin Asid to estimate the yield of grapes just as the yield of dates is estimated. Then, the zakat should be paid from raisins, just as the zakat of dates is paid from dried dates. This was the practice of the Holy Prophet (peace and blessings be upon him) regarding dates and grapes.